Learn about styles (read this first)

How a mind map looks is controlled by styles. The styles control everything, such as colors, topics, lines, font size, and more. Pick a style sheet to set the default style for the mind map. Customize the details by changing the style of one or more of the elements.

Style Sheet:
Top level. The style sheet controls most of what you see in the mind map. When no other style settings are applied, the Style Sheet defines the appearance of the mind map.
Select any of the default style sheets, or create your own custom style sheet.

Mind Map Style:
Use the mind map style to redefine aspects of the selected style sheet, for that mind map only.
For example, to change the background color for one mind map. Or the color of the relations.

Element Style:
Use the element style to redefine the appearance for a single element. For example, to make one crosslink red.

Additionally, set Preferences that operate on a global level for all mind maps.

Tip: The layout of a mind map, how topics are organized, is set via layouts.